It looks gorgeous. Probably a vine snake, mildly venomous but largely harmless. Likes frogs, etc. Look carefully in your garden and you may find one, though that's difficult because she's a wonder at disguise and will look no different from your normal green stem, stalk.
Wonder what she's doing in that concrete jungle called TTK Road though. Probably an adventure seeker, and wanted to boldly go where no vine snake had gone before!